This circuit was found in an American medical documentation from 1970. The circuit rejects the 60 Hz noise pickup and generates 2.5 Hz signals. Equivalent components can be tested.
This signal follower, from a publication from the 1970s, uses old germanium transistors such as...
Although it is a common configuration today, this circuit was taken from an old publication. The...
This circuit for the 85 to 95 MHz band has a gain of 15 dB. We find it in a 1980s documentation. The...